John b



J. B. WIARD.

HIGH SPEED GRINDING MACHINE.

A'rmcmon FILED JULY 3.191s.

1,304,229. Patented May 20, m9.

' 27 I8 imW /////////4 QWIIM Inventor: John 'B.Wi ar-d,

- To tut w/wm at mag sc oncem:

srarns {PATENT OFFICE.

JOHN 3. ml), or LYNN, m lssaon'usnrrs, nssrenon. T GENERAL ELECTRIC comm, a CORPORATION or New YORK.

HIGH-SPEED GRINDING-MACHINE.

Application filed July 8, 1915. Serial 11 038,020.

.Be it knownthat I, JOHN B. Wnuzn, a

- citizen of the United States, residing at :Ifiynn, in the county-of Essex, State of ass'achus'etts have invented certain new and useful Improvements in High-Speed 'Grinding-Machines,-of which the following is a specification. I

My invention relates to machines having a rotatably mounted-spindle adapted to be driven at high speed, and in particular to high speed grinding machines-,such for example as-are employed for grinding ball.

bearing races and the like.

' .The bject of" y invention is to provide a novel and improved construction of-electrically-driven machine having a rota.-

table spindle ada ted to be driven at high speed, and partic arly of electrically-driven grinding machines adaptedto be Operated at high speed. -The novel. features which I believe to be patentably characteristic of my invention aredefinitely indicated in the claims appended hereto; the construction and mode of operation of a high speed machine embodying these features will be understood from the following .de-

l scription taken in connection with the ac:

. companying drawings, in which:

Figure 1 is anelevation of a high speed a grinding machine embodying the novel features of .myt-present invention, and :Figs. 2

and 3 are sectional views ofthe electricallydriven'spindle showing the electric motor elements assembled and disassembled, re-'.

spectively,- and Fig. 4 is a modification.

High s eed grinding machines, such as those emp oyed for grinding out the inside of ball-bearing races, use very small grinding wheels rotating at high speed, such for example as 5,000 to 25,000 revolutions per minute. The spindles of'such'machines have heretofore been generally belt driven, andsuch high speed 0 "considerable diflic ty and -for,thi's reason,

' among others, the electric drive has not been generally adopted in high speed grinding machines. A twoypole-induction motor operating on a commercial circuit of 60 ccl'es has'a synchronous speed of only 3,600 P.

' M.,yvery much too low for a h gh .speed grindingmachine. It has been found pract cable in electrically-driven high speed .grlnding machines to employ a frequency changer, such as a motor-generator set, op-

crating from a commercial circuit of 60,

cycles and producing alternating current of much higher frequency, such as 100 to 450-cycles. With alternating current of 100 induction motors have heretofore been directly connected to the spindle of the grinding machine, which of course is provided with its own bearings, so that there are four bearings in a line, two belonging to the spindle of the grinding machine and two belonging to the electric motor. The use of four bearings in a line isfobvious'ly most undesirable, particularly at such high speeds as hereinmentioned. The aim. of my present invention is to provide high speed grinding machines with an efficient, practical and .in

all respects satisfactory form ,of electric drive. This I accomplish'by constructing the electric motor as a part of the grinding machine, with the electric motor elements removably mounted, so that these elements may be supplied as separate units and mounted in the grinding machine in the course of the latters construction.

My invention will be best understood by reference to the accompanying drawings.

In Fig. 1-, I have illustrated a typical form of 'highfspeed grinding machine having a flat bed. or table 5 supported upon a base or pedestal 6.' A carriage 7 is suitably mounted upon the table 5 and is adapted to bemoved longitudinally by a wheel 8 and transversely by-a wheel 9. A chuck or other work-carrier 10 is suitably mounted in a stationary head Hand is adapted to be driven by a belt 12.} a The carriage or -grinding head 15 having a housing 16 7 includes a supporting base I therein. The base 15 has a circular bore 17 communicating with the housing 16, and mounted in this bore are two bearings '18 for the spindle-19; of the machine. The

andis tapered at this end, as clearly shown spindle extends at one end into the housing I grinding wheel 20 ofcarborundum, or other I ductlon motor for alternating current of relatively high frequency. The housing 16 is'formed with suitable material, is secured to the end of the spindle exteriorly of the housing 16.

r The rotor element 21 of an induction elec tric motor is positioned within the housing- 16 and is adapted to be removably secured to the tapered end of the spindle 19. The rotor element 21 illustrated in the drawings comprises a laminatedmagnetic core carrying a squirrel cage winding of east alumi-' num. Cast aluminum gives'a particularly .solid rotor construction which when oncethe casing 16.. This stator element.com-.

prises a laminated magnetic core and an inprimary winding designed a shoulder 25 which serves to accurately position the stator. The stator element is- 'mounted in the housing as a unit, andis secured in position by a screw-threaded ring die.

"sesses m i it 26. A cover 27 closes the end of the housing afterthe motor elements have-been secured in their operative positions;

The housinglfi serves as a frame for the motorand at -'the' same time is an integralpart of the grinding head. Theispindle 1-9 of the motor n, an over-.

supports the rotor hung fashion, and the only bearings for the I spindle are positioned exteriorly of the housmg and henoe of the motor elements. The

external surfaces of the housingand cover are ribbed, as indicated in Figs. 2 and 3', t0

increase their heat radiating surfaces, since a comparatively large amount of power is. de- I veloped in a verysmall'space, and hence a relatively large amount of heatinust be ra-.

diated.

The construction of an electrically driven grinding achine asherein described posy advantages. For such hi h speeds asare herein contemplated, it is a d1. ficult'and delicate problem to -couple an independent electric motorto a rotatable spina The shaft of the motor must bein eX -g' .act alinement with .the spindle, and to this end four bearingshave to be alinedifln ac cordance w th ny-present invention; there employedia fsihg1e.'sh ;ft '01 spindllhilvihgi atein armedwsupne bi' .only one set fofi bearings. Thehousing o frame of such machine. The'roumand' stator elements of the electric motor can be 'independenly manufactured to s'uitthe specifications,

of any particular grindingmachine, and are thusforming when assembled a part-0t the "for preventing V v motor parts forced-ventilatiommay he I ployed. Fig'.-;. of so" air., Suitable outlet ports 45 are also pro:

'tdsaidjstator, the other and 9f,

for-the electric'motor elements-is an integral part of thegrindingmachine, and J is formed 1n the course of the menu-imamthe like comprising; 111

formed integra I grinding machine itself.v 1 A manufacturer of. grinding machines need thus'secure a manufacturer of electrical apparatus only? the",'rotor and 'statorelements' of 'an electric! motor, and can assemble these elements in $170 frame built 'as apart of the "grindingflmav chine. The cost of theelectric driveis thus II lowered, and a very 'conmactv structure -se- In cases where the heat radiatingmeans-n' provided by ribbing or corrugating theexterior surface of the housing 16 is insuificient objectionable'heating. off the modified construction H I, ing purposes. The rotor element J41; cast squirrel cage'winding, for exampl" aluminum, with integral fan blades This integral cast construction of an-indujce 135- tion motor secondary windingis dsqribed and claimed inmy. application for'Let'ters'. Patent, 'Ser. No. 3224, filed J 191 .31 Thecover-47 is provided-with a centralopenr 'ing 48-forthe intake of the ventilating"a.ir-. go. The opening 48 is preferably provided'with';

.a screen 49. :The interior of the housmg 16',

--'of Fig. 'is' provided with -ducts'4=6, providing transverse passages forthe ventilating,

vided in'the housing. The arrows indicate the paths provided through the motor struc-.

ture for the ventilating air. It will be derstood that the housing and stator element are otherwise of the same construction anddesign aseXplained-in connection with Figs.

2 and 3. v

What I claim as newanddesire to secure by Letters Patent of the United States, is v 1.:A high speed machine for grinding cr me the like comprising in combinatlon'a sup porting 'member having but one bearing formed integrally therewith on one .-'end' thereof,- a spindle rotatably mounted there-- in, the other end of'said supporting member being 'hollewed out to form a. cup-shaped motor housing having its interior surface formed concentric with and surrounding said spindlaian electric motor stator removably secured within said housing and m engage- 1 15 'ment with the interior surface of housing, and ang electric motorrotor removably mountedionilione "end of said spindle intehous'ing'in operative relation.

saidspilidle -A- x ed mw m om hmationiza-sup-g orly of ifsaid "I l i n'f"o ne end 12 thereof, .a- "spindle"havmg it mjd.- ti my I mtably m un d-a in said. bearing and arlowed out form a cup-shaped motor housing having its interior surface formed concentric with and surrounding said spindle, an. electric motor stator .removably'; secured Within said housing and in engagement with the interior surface of said housing, and an electric motor rotor removably mounted on one end of said spindle interiorly of. said houslng in operative relation to said stator,

the other end of said spindle being formed 10 i to support a grinding tool.

In witness whereof, I have hereunto set my hand this 30th day of June, 1915.

. JOHN vB. WIARD. 

